Figure 2.

a Relation between the reaction time and temperature (C_gelatin: 0.4 wt%), The reaction time was determined by UV–vis spectra. When the typical absorption band of gold nanoparticle was stable, the reaction is considered to be over; b UV–vis spectra of gelatin-AuNPs colloids synthesized at different temperature (1) 100°C, (2) 80°C, (3) 60°C.